Use of L-deprenyl for retention of specific physiological functions

ABSTRACT

L-Deprenyl and pharmaceutically acceptable analog forms thereof are used at specific dosage levels and frequency of dosage to slow the normal age dependent deterioration of renal function, to provide increased exploratory behavior level of activity at any given age and in order to retard age deterioration of cognitive abilities, especially spatial learning ability. The treatment can be especially useful for mammals, for examples pets such as dogs and cats.

BACKGROUND OF THE INVENTION

1-Deprenyl is a selective monoamine oxidase B (MAO-B) inhibitor, whichis widely used as an adjunct in the treatment of Parkinson's disease.While it's most common usage is for the treatment of Parkinson'sdisease, 1-deprenyl was originally developed as an antidepressant agent.Recent testing has indicated that 1-deprenyl may have some effect onincreasing sexual response in aging animals, and also may have someeffect, at least in rats in increasing the natural life span. However,to date 1-deprenyl has only been medically approved by regulatoryagencies for use for treatment of Parkinson's disease.

The search for new lines of medication to improve the quality of life insenescence ever continues. This becomes especially important inmodern-day society, especially in developed countries, where theproportion of citizens over 65 years of age continues to increase. Insum, the quality of life has become increasingly important in olderyears, as people continue to experience longer life expectancy.

There is, therefore, a continuing and real need for the development ofmedications which retard the normal deterioration of certainphysiological functions.

It is a primary objective of the present invention to develop a dosageregimen for the use of 1-deprenyl to retard deterioration of normalrenal function with age, to retard deterioration of cognitive abilitiesduring advanced aging, and to retard the deterioration in the naturaltendency for curious or exploratory behavior in aged mammals, such aspets like dogs and cats.

While 1-deprenyl is a known compound, it has never before been used atany level to retard physiological effects of age deterioration oncertain organs, such as kidneys, nor to retard cognitive abilitydeterioration with age.

Like most drugs, 1-deprenyl can have diverse physiological effects whichare completely dependent upon the dose administered. In accordance withthe present invention, 1-deprenyl can be used for successful methods oftreatment to provide the desired physiological effects enumeratedherein, providing that it is used at the dosage levels mentioned hereinand providing it is administered at the periodic intervals and for thetime spans mentioned herein. Obviously, when different dosages andlevels of treatment are used, the results expressed herein may not beachieved. In fact, at higher doses, adverse behavioral effects may beencountered.

SUMMARY OF THE INVENTION

The present invention relates to the process of using a known compound,1-deprenyl, for new uses. In particular, at the dosage levels describedherein, providing that the dosage is used for at least the periods oftime expressed herein, there is an observed retardation of normal agedependent deterioration of renal function and an observed retardation ofnormal degeneration of cognitive abilities, including spatial learningability. Further, the age-dependent weight loss may also be avoided. Thetreatment is especially useful for domesticated pets, like dogs andcats, as they increase in age, but would be expected to have utility inany mammal species.

DETAILED DESCRIPTION OF THE INVENTION

As earlier stated, the compound that is useful for the method orprotocol of the present invention is a known compound, 1-deprenyl.1-Deprenyl has the formula(-)-N-α-dimethyl-N-2-propynylbenzene-ethanamine. It can be illustratedby the following graphic formula: ##STR1##

1-Deprenyl also is at times referred to as L-deprenyl to illustrate thatit is a levorotary isomer which is the active form for treatment ofParkinson's disease. Typically, it is provided in a pharmaceuticallyacceptable salt form thereof such as the hydrochloride salt.

As used here, pharmaceutically acceptable salt form thereof, means thefollowing. Acceptable for use in the pharmaceutical or veterinary art,being nontoxic or otherwise not pharmaceutically or veterinaryunacceptable. "Acceptable salt form thereof" means salts formed withinorganic acids such as hydrochloric acid, hydrobromic acid, sulfuricacid, nitric acid, phosphoric acid, and the like, and as well organicacids such as acetic acid, propionic acid, glycolic acid, pyruvic acid,oxalic acid, malic acid, malonic acid, succinic acid, maleic acid,fumaric acid, tartaric acid, citric acid, benzoic acid, cinnamic acid,mandelic acid, etc.

Administration of the therapeutically active compound 1-deprenyl toachieve physiological results of the present invention can be via any ofthe accepted modes of administration for systemically active substances.These methods include oral, parenteral, and otherwise systemic, aerosol,and topical forms, as well as sustained release systems, etc.

The compositions of the present invention may be any of those known inthe pharmaceutical and veterinary arts which are suitable for the methodof administration and dosage required in any particular circumstance. Inthe case of both pharmaceutical and veterinary applications, suchcompositions may include tablets, pills, capsules, powders, aerosols,suppositories, skin patches, parenterals, and oral liquids including oilaqueous suspensions, solutions and emulsions. It may include long actinginjectables and sustained release devices.

When the dosage is in solid form, solid pharmaceutical carriers such asstarch, sugar, talc, mannitol, povidone, magnesium stearate, and thelike may be used to form powders. Lactose and mannose are the preferredsolid carrier. The powders may be used as such for direct administrationto a patient or, instead, the powders may be added to suitable foods andliquids, including water, to facilitate administration.

The powders also may be used to make tablets, or to fill gelatincapsules. Suitable lubricants like magnesium stearate, binders such asgelatin, and disintegrating agents like sodium carbonate in combinationwith citric acid may be used to form the tablets.

Unit dosage forms such as tablets and capsules may contain any suitablepredetermined amount of 1-deprenyl, advisably as a nontoxic acidaddition salt, and may be administered one or more at a time at regularintervals as later described. Such unit dosage forms, however, shouldwith a broad range guideline contain a concentration of 0.1% to 10% byweight of one or more forms of the active 1-deprenyl.

A typical tablet may have the composition:

    ______________________________________                                                      Mg.                                                             ______________________________________                                        1. 1-Deprenyl   10.0                                                          2. Mannitol     100                                                           3. Stearic acid 3                                                             ______________________________________                                    

A granulation is made from the mannitol. The other ingredients are addedto the dry granulation and then the tablets are punched.

Another tablet may have the composition:

    ______________________________________                                                       Mg.                                                            ______________________________________                                        1. 1-Deprenyl    10                                                           2. Starch U.S.P. 57                                                           3. Lactose U.S.P.                                                                              73                                                           4. Talc U.S.P.    9                                                           5. Stearic acid   6                                                           ______________________________________                                    

Powders 1, 2 and 3 are slugged, then granulated, mixed with 4 and 5, andtableted.

Capsules may be prepared by filling No. 3 hard gelatin capsules with thefollowing ingredients, thoroughly mixed:

    ______________________________________                                                       Mg.                                                            ______________________________________                                        1. 1-Deprenyl    5                                                            2. Lactose U.S.P.                                                                              200                                                          3. Starch U.S.P. 16                                                           4. Talc U.S.P.   8                                                            ______________________________________                                    

As earlier expressed, physiological functions effected by the treatmentherein with 1-deprenyl are necessarily dosage dependent. Put anotherway, like most drugs, 1-deprenyl has diverse physiological effectsdepending upon the dose administered. Unless the dose administered iswithin the levels set forth herein, the desired effects on renalfunction, weight retention, and cognitive processes are not achievedwithout adverse effects.

While the tests later described herein are only provided for testing ofmale Fischer rats purchased from Harlan Spraugue Dawley, the tests are afair generalizations for mammals. And therefore, the term mammal as usedherein includes without limitation humans and domesticated animals suchas cattle, horses, swine, sheep, dogs, cats, goats and the like. Thetests are particularly illustrative for domesticated pets such as dogsand cats. The treatment may even work for birds or fish.

Renal function and cognitive abilities for dogs and cats are especiallyimportant as they age. Among other reasons, this is in part becausehumans form quick and strong bonds with their domesticated pets, andthese strong bonds increase the desire to keep the animal alive for manyyears, often well beyond the peak years of efficient organ function andpeak cognitive abilities. This may cause many problems if the animal isa house pet.

Needless to say, the natural enjoyment of these pets would besignificantly increased in their older age if one could retard thedecrease in physiological functions and cognitive processes. Forexample, it often happens that older dogs and cats increasingly losetheir renal function. Moreover, as dogs and cats get older, they usuallyhave decreased cognitive functions, especially a decrease in spatiallearning ability and their natural exploratory behavior, i.e. level ofcuriosity. These natural changes alter the animal's personality suchthat the human owner has less enjoyment from the animal.

In accordance with the present invention, it has been illustrated therenal function deterioration can be retarded, and in fact exploratorybehavior can be increased in older animals, and cognitive abilitydeterioration can be retarded, especially spatial learning ability ifthe animal is treated periodically with small but therapeuticallyeffective doses of 1-deprenyl. Additionally, age-dependent weight losscan be prevented.

As hereinafter explained, the dosage regimen to achieve these desirableresults differs considerably from the dosage regimen used in treatingParkinson's disease. At the highest doses recommended for uses disclosedherein, the levels are less than one-half the amount used for treatingParkinson's disease. In particular, the dosage regimen of the presentinvention shows usage at levels from about 0.01 mg/kg of body weight upto about 1.0 mg/kg of body weight from one to seven times weekly, butpreferably on alternate days. Most preferably the dosage level is0.05-0.5 mg/kg of body weight given twice weekly, starting in middleage. Of course it would be known to those in the art that sustainedrelease systems can be used to provide less frequent dosing to achievethe required dosage level.

It is not known precisely why the use of 1-deprenyl at the dosage levelsand periodicity expressed herein achieves these results. While notwishing to be bound by any theory of operation of the present process,it is believed that rather than central processing in the brain theremay be a direct effect on the kidney. The effect may be hypotensive. Asexplained in the examples below, analysis of serum chemistry suggeststhat the 1-deprenyl treatment may have a direct effect on kidneyfunction. With regard to the cognitive processes, it is simply not knownby what mechanism the compound works, except to say that it iscritically important that the dosage be at levels expressed hereinrather than in Parkinson's disease levels, otherwise adverse effects maybe achieved, particularly in dogs.

In the tests and examples reported hereinafter, differences in renalfunction between control and 1-deprenyl treated animals was measured byan examination of blood chemistry and in particular the level of bloodurea nitrogen (BUN), which is a measure of waste product which iscleared from the body by the kidneys. High levels are indicative ofineffective renal function, and low levels are correspondingly anindication of proper renal function.

Tests of cognitive ability, i.e. memory and response acquisition, weremeasured in a water maze test. The particular animals were placed in awater maze, as described below and given 90 seconds to swim and locate aplatform and climb upon it and escape from the water, for which theseanimals show a natural aversion. Repeat testing continued until theanimals learned that once placed in the water they could swim to theplatform and easily prevent drowning. Memory was measured by the abilityof the rat to retain this learned behavior five days following the lastmaze test. In particular, five days after the maze test, the rats wereplaced in the water maze again, with the platform removed. As aretention measure, time spent in the region of the maze where theplatform would normally have been was recorded. The same procedure wasrepeated twice more each time with the platform in a new location. Bydoing so, the animals' ability to profit from its previous experiencewas tested.

During the late stages of aging, rats show a progressive decrease inbody mass, and an examination of individual data indicates thatdecreased body weights proved to be a reliable predictor of death. Inthe test data of the rats studied in the examples, body weights of thecontrols and the 1-deprenyl treated rats were recorded. It was uniformlyobserved that normal age dependent body mass loss was retarded in the1-deprenyl treated group and that this was not associated with dietarydifferences. In sum, at advanced stages of aging, the surviving1-deprenyl rats were significantly heavier than the surviving controls.

EXAMPLES

In the examples below, male Fischer rats from Harlan Sprague Dawley wereused. The animals were obtained at 21-23 months of age. They wereallowed free access to food and water, and were weighed on every otherday.

1-Deprenyl treatment was started when the animals were between 24 and 25months of age. The drug was administered subcutaneously at a dose of0.25 mg/kg on alternate days until the animal either died or was removedfrom the experiments. The deprenyl was dissolved in a solution ofsaline.

Serum analysis was done on the animals on two occasions, at the start ofthe experiment, and again after 3 months of treatment. The blood sampleswere taken intraorbitally, which could only be done on anesthetizedanimals. As an anesthetic, a mixture of equivalent volumes of ketamineand atravin were used because the combination has a low toxicity, andshort duration of effect in young rats. In the baseline test, a dose of0.2 ml was used. However, this induced a much deeper and longer lastingperiod of anesthesia than was desired and the dosage was subsequentlyreduced to 0.08 ml for the three month test.

The samples were immediately sent to Vita-Tech Canada, where biochemicalassays were done for: glucose, creatinine, bilirubin (total), blood ureanitrogen (BUN), SGOT, SGPT, total protein and albumin. For analysis ofhematology, measurements were taken of hemoglobin, hematocrit, RBCcounts, WBC counts, MCH, neutrophils, lymphocytes, monocytes,eosinophils, Basophils, and nRBC. A double blind procedure was followedin collection and analysis of serum biochemistry and hematology. Theresults of the serum analysis are summarized in Table 1. The onlysignificant difference between the controls and 1-deprenyl group atthree months was in the measure of (BUN). The comparisons for creatinine(p=0.129), albumin (p=0.117) and A/G ration (p=0.151) were close to thesignificance level, while there were clearly no differences in bilirubin(p=0.826), SGOT (p=990) and SGPT (p=0.667). Table 1 shows thecorrelation between each of the measures and survival. The levels ofBUN, SGOT and bilirubin all correlated significantly.

                                      TABLE 1                                     __________________________________________________________________________    Effect of 1-deprenyl on Measures of Serum Chemistry                                     BASELINE             3 MONTHS                                                                 Corre-               Corre-                                                   lation               lation                                   Control Deprenyl                                                                              with Control Deprenyl                                                                              with                           Measure   N = 24  N = 29  survival                                                                           N = 22  N = 23  survival                       __________________________________________________________________________    A/G Ratio  .97 ± .02                                                                          .97 ± .03                                                                         .10   .75 ± .02                                                                          .81 ± .04                                                                         .14                            Albumin g/L                                                                             29.92 ± .71                                                                        29.76 ± .89                                                                        .13  24.0 ± .73                                                                         25.62 ± .74                                                                        .51**                          Bilirubin umol/L                                                                        3.05 ± .25                                                                         2.93 ± .24                                                                         -.26 4.19 ± .41                                                                         4.43 ± .98                                                                         -.35                           BUN mmol/L                                                                              8.45 ± .29                                                                         8.18 ± .22                                                                         -.12 14.02 ± 1.61                                                                       .sup. 9.95 ± .45.sup.1                                                             -.51**                         Creatinine umol/L                                                                       73.13 ± 1.97                                                                       70.93 ± 1.61                                                                       -.01 85.28 ± 5.82                                                                       75.52 ± 2.68                                                                       -.13                           Glucose mmol/L                                                                           7.73 ± 1.03                                                                       7.19 ± .73                                                                         .11  7.87 ± .76                                                                         8.50 ± .62                                                                         .38*                           Total Protein g/L                                                                       60.58 ± 4.93                                                                       60.31 ± .95                                                                        .17  56.73 ± 1.47                                                                       57.69 ± .93                                                                        .57**                          SGOT U/L  108.96 ± 8.43                                                                      121.41 ± 1.10                                                                      .07  135.32 ± 17.10                                                                     135.79 ± 32.00                                                                     .47                            SGPT U/L  63.96 ± 4.72                                                                       64.52 ± 4.56                                                                       .05  60.04 ± 6.03                                                                        67.04 ± 14.68                                                                     .45*                           __________________________________________________________________________     Scores represent means ± SEM. Correlations are with days survival from     the start of the experiment.                                                  .sup.1 significantly different from controls using a twotailed test (P =      .017)                                                                         *significant at .01 level                                                     **significant at the .001 level                                          

The blood chemistry data were informative, and provide a possibleexplanation as to why animals treated with 1-deprenyl survived longerthan the controls. At 26 months, there was a significant difference inthe measure of BUN, with the deprenyl group having a lower score thanthe controls. BUN is a measure of a waste product which is cleared fromthe body by the kidneys. High levels are therefore indicative ofineffective renal function. Differences in renal function between thedeprenyl group and the control group were also indicated by thedifferences in amounts of creatinine (deprenyl lower than controls),although the size of the differences did not achieve statisticalsignificance.

In a comparison between 23 and 26 month animals, it was found that bothBUN and creatinine were significantly higher in the 26 month test. Theseresults were not unexpected, since it is known that the rat, like othermammals, shows marked deterioration of renal function with advanced age.The significant drug effect at 26 months therefore is indicative of1-deprenyl treatment providing protection of renal function. That suchprotection is associated with survival is further indicated by thesignificant correlation between BUN measure and days of survival in the26 month group.

The absence of differences between the deprenyl and controls on theother biochemical measures may be indicative of deprenyl affecting thekidneys to a greater extent than it does other peripheral organs, orthat the rats were too old at the start of treatment.

The water maze consisted of a circular chamber filled with water to adepth which just covered the surface of a transparent platform, 17.75 cmin height. At the start of each session, the rat was placed in the tankfacing the outer surface at a randomly determined point, approximately 1meter from the center of the platform. Animals were given 90 seconds tolocate and climb upon the platform. The animal was removed from theplatform after 30 seconds. A correction procedure was used. If theanimal did not find the platform, it was gently guided to it at the endof the trial, and removed after 30 seconds Testing continued untileither the criterion of escaping onto the platform within 25 seconds onfour out of five consecutive trials was achieved or 30 trials had beencompleted. A maximum of ten trials were given each day, with an intervalof 30 minutes between each trials. Every trial was also videotaped.

Retention was tested five days following the last acquisition trial byplacing the rats in the maze for three 90 second trials with theplatform removed. As a retention measure, the time was recorded that wasspent in the region of the maze where the platform had earlier beenlocated. A second set of acquisition trials were then given using sameprocedures followed during the original training, except that theplatform was moved to another location. Following acquisition andsubsequent retention trials, the animals received a third set oftrials--again with the platform at another position. Thus, each animalwas tested for both acquisition and retention on three separateoccasions.

Changes in cognitive abilities of animals treated with 1-deprenyl andcontrol were measured in the water maze test, earlier described.

Water maze acquisition was tested in 16 animals (8 deprenyl and 8control) at 26 months. The deprenyl group were tested while in theirthird month of drug treatment. An additional three animals started thetesting, but were dropped because of inability to swim acceptably. At 29months, 9 animals (5 deprenyl and 4 controls) were tested on the watermaze. The deprenyl animals were in their sixth month of drug treatment.Five additional rats were unable to swim or were moribund at the startof testing.

Analysis of water maze acquisition was based upon the number of trialsrequired to reach criterion. A maximum score of 33 was assigned if ananimal did not learn the task within the three day test period. Theresults are summarized in Table 2. An analysis of variance with age andsession as main effects indicated a significant age effect reflectingslower learning in the older animals (F(2,58)=10.5, p=0.00), and asignificant session effect reflected improvement in learning overrepeated testing (F(2,58)=11.12, p=0.00). There was also a tendency forthe younger animals to show greater improvement, although the age bysession interaction was not significant (F(6,58)=1.64, p=0.152).

To test for drug effect in acquisition, the 26 and 29 month animals werecompared with a three way analysis of variance with age, group andsession as main effects. There were significant main effects for age(F(1.21)=4,62, p-0.143) and session (F(2,42)=2.55, p=0.29). The groupeffect was not significant, the age by group interaction was highlysignificant (F(2,42)=12.2, p=0.002). As indicated in Table 2, thisfinding is attributable to the deprenyl group performing poorly whentested at 26 months, and better than the controls when tested at 28-29months.

The results of the retention tests, on the other hand, did not revealany consistent effects of group or age.

                  TABLE 2                                                         ______________________________________                                        Means trials to criterion (± SE) in water maze as a function               of age, treatment with L-deprenyl and previous trials                         Age                                                                           (month)                                                                              Group    N       Test 1 Test 2 Test 3                                  ______________________________________                                         7     Control  9       15.67 ±                                                                           10.67 ±                                                                            9.33 ± 2.03                                                 1.91   3.18                                           23     Control  12      18.50 ±                                                                           12.25 ±                                                                           5.67 ± .86                                                   2.49   2.83                                           26     Control  8       17.88 ±                                                                           15.87 ±                                                                           8.00 ± .96                                                   3.86   1.87                                                  Deprenyl 8       22.63 ±                                                                           22.38 ±                                                                           21.75 ± 3.58                                                 3.54   3.85                                           29     Control  4       31.00 ±                                                                           26.25 ±                                                                           29.00 ± 4.67                                                 0.71   5.81                                                  Deprenyl 4       25.40 ±                                                                           17.20 ±                                                                           13.80 ± 5.07                                                 2.69   4.22                                           ______________________________________                                    

The control rats showed better acquisition at 26 months than thedeprenyl group, while at 29 months the results were reversed--with thedeprenyl group showing superior learning. The poor acquisition seen inthe 26 month deprenyl-treated rats was largely due to difficulties inreversal--that is, in relearning the task after the position of theplatform was changed. At 29 months, the deficits in the control groupreflected a general retardation, indicated by an inability to solve theproblem, and are indicative of severe cognitive impairment.

There is no obvious explanations for the results from the 26 monthgroup, but it can't be ruled out that there is a possibility, however,of deprenyl producing a transient cognitive disruption. Very likely someperiod of time is required on the drug before the animals fully adjustto it. It could, however, be concluded from this data that the deficitswere not permanent. To the contrary, the 29 month old animals ondeprenyl showed significantly better learning than the controls.

When compared with saline-treated controls, the 1-deprenyl treated ratssurvived longer, appeared healthier, showed more exploratory behavior,and less evidence of mental retardation at 29 months. Additionally, theydid not lose as much body weight.

Finally, it should be emphasized that the data presented herein is withregard to rats as the exemplary mammal. It is known, however, that it isvery likely that 1-deprenyl will have similar effects in correlation inthe human, primate, dog and cat brain. This is strengthened by strongknown evidence that this exact parallel finding in humans withParkinson's disease correlates precisely with similar findings in agedrats. Thus, the scientific correlation between the rat model and othermammals is known and recognized by those skilled in the art.

It therefore can be seen that this invention accomplishes at least allof its stated objectives

What is claimed is:
 1. A method of treating dogs for the purpose ofinducing therein at least one physiological effect evidencing a decreasein cognitive dysfunction, said effect selected from the group consistingof spatial learning, exploratory behavior, and memory responseacquisition, said method comprising:administering to the dog from one toseven times weekly a small but cognitive dysfunction treating effectiveamount of the compound 1-deprenyl or a pharmaceutically acceptable saltform thereof.
 2. A method of treating cognitive dysfunction of dogs,said method comprising:administering to the dog from one to seven timesweekly a small but cognitive dysfunction treating effective amountwithin the range of from 0.01 mg/kg of body weight to 1.0 mg/kg of bodyweight of the compound 1-deprenyl or a pharmaceutically acceptable formthereof.
 3. The method of claim 2 wherein the 1-deprenyl is thehydrochloride addition salt form thereof.
 4. The method of claim 2wherein the addition level is from about 0.05 mg/kg of body weight toabout 0.5 mg/kg of body weight, dosed at least twice weekly starting inmiddle age.